This invention relates to a process for making 2-oxindole-1-carboxamides which comprises reacting a 2-oxindole with chlorosulfonyl isocyanate to produce a novel N-chlorosulfonyl-2-oxindole-1-carboxamide which is then hydrolyzed to a 2-oxindole-1-carboxamide. Said 2-oxindole-1-carboxamides are useful as intermediates for analgesic and antiinflammatory agents.
The reactions of chlorosulfonyl isocyanate with various nucleophiles, including amines to produce N-chlorosulfonylamido (ClSO.sub.2 NHCO) derivatives thereof, and subsequent hydrolysis of said derivatives to afford amides is described by Graf., Angew. Chem. Internat Edit, 7, 175 (1968); Rasmussen et al., Chem. Rev. 389-390 (1976); and Szabo, Aldrichimica Acta 10, 23 (1977).
The preparation of 2-oxindole-1-carboxamides by cyclization of the appropriate (2-ureidophenyl)acetic acid by means of, for example, trifluoroacetic anhydride/trifluoroacetic acetic acid is described in U.S. patent application Ser. No. 684,634, filed Dec. 21, 1984, now U.S. Pat. No. 4,556,672, of Saul B. Kadin, entitled 3-Substituted 2-Oxindole-1-carboxamides as Analgesic and Anti-inflammatory Agents.
The process of this invention represents an improved process for making 2-oxindole-1-carboxamides of formula III in good yield and purity from starting materials which are readily available.